county in the province of Leinster, north-central Ireland. It is bounded by Counties Leitrim (northwest), Cavan (northeast), Westmeath (southeast), and Roscommon (west). The main features of drainage are the valleys of the Rivers Shannon, Erne, and Inny and Loughs (Lakes) Gowna and Ree. The surface of the county, generally a part of lowland Ireland, rises from the Shannon to 200-400 feet (60-120 metres), but there are isolated hills and ranges. The lowland is thickly plastered with glacial drifts and has large areas of bog